Allen-Bradley Compact I/O 1769-ADN DeviceNet, User Manual

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Publication 1769-UM001B-EN-P - October 2002
6-36 Application Examples
Data Table Address (Receive and Send)
This value identifies the data file location within the 1764-LRP
controller that will receive data from the DeviceNet device, and/or the
starting data file location that will be sent to the destination DeviceNet
device.
Size in Bytes (Receive and Send)
Since all data transmitted on DeviceNet is byte based, you must enter
the number of bytes that will be received and sent. You must make
sure that enough memory is available in the destination device. Word
elements within 1764-LRP controllers contain 2 bytes each. These
include Bit and Integer data files. Long word and Floating point
elements contain 4 bytes each.
For receive, the Size in Bytes entered must be greater than or equal to
the number of bytes than the DeviceNet device will return. DeviceNet
devices return a fixed number of bytes depending on the Class and
Service. If more data is returned than expected, the message will error
and no data will be written. If less data is returned than expected, the
data will be written and the remainder of the bytes will be filled with
zeros.
In the example screen shown below, N7:0 will receive 2 bytes (1
word) of data.